The present invention relates to regulating movement of a seat back assembly in a vehicle and, in particular, to controlling movement of a seat back assembly using one or more initiator assemblies.
Numerous vehicle safety systems have been advanced and used in protecting the occupants in the vehicle when a collision occurs. Air bag modules that inflate when activated using inflators have been integrated with vehicles to safeguard the driver and/or passenger(s). Seat belt pre-tensionors have also been devised that activate under vehicle collision conditions. Additionally, vehicle seats have included mechanisms that control movement of the seat back, particularly when the vehicle is subject to a front or rear end collision.
In conjunction with seat back assemblies, it is desirable to dampen their movement in a predetermined manner in order to reduce the severity of an injury to a vehicle occupant including whiplash injuries. Because of the potential seriousness of head, neck and back injuries that can result from front and rear end collisions, it would be beneficial to provide a system in the vehicle that functions effectively to regulate seat back movement when these types of collisions occur. As part of such a vehicle system, a mechanical control assembly is necessary to properly regulate seat back movement. It would be advantageous to provide such a control assembly that is also relatively easily to manufacture, has a limited number of parts and can be produced at a competitive cost.
In accordance with the present invention, apparatus and method are provided for controlling movement of a seat back in a vehicle using a control assembly that includes at least a first initiator assembly. The control assembly is operably connected to a seat back assembly associated with the vehicle seat including back. When a front or rear end collision occurs that exceeds a predetermined threshold, the control assembly can be activated to regulate movement of the seat back.
In a preferred embodiment, the control assembly includes a piston assembly that is operably connected to the seat back assembly. The piston assembly includes parts that controllably change position in connection with causing the seat back to move when a collision occurs. The piston assembly includes a housing having a chamber for containing damping fluid. The piston assembly also includes the piston head and a shaft connected thereto. The diameter or width of the piston head is substantially the same as the inner diameter of the chamber. Preferably, one or more sealing members or rings are located outwardly of the circumference of or periphery of the piston head and engage the inner wall of the housing. In one embodiment, the piston head includes at least one bore or hole that extends through the piston head. The bore permits damping fluid to move between opposing sides of the piston head. The shaft extends from one of the sides of the piston head and can extend outwardly from the housing to, directly or indirectly, operably connect to the seat back movement assembly.
The control assembly also includes a transfer assembly comprising a number of parts or sections, which are involved in transferring damping fluid from one side of the piston head to the other side, depending upon whether or not a front end or rear end collision has occurred, when the control assembly is activated. The transfer assembly includes at least a first transfer member that can be defined as including first and second transfer member sections and a juncture therebetween. The juncture has two states, namely, an open state and a closed state. In one of these two states, the control assembly is activated and, in the other of the two states, the control assembly is unactivated. In one embodiment, in the closed state of the juncture, the control assembly is unactivated and the juncture changes to the open state, after the control assembly has been activated. In regard to this one embodiment, this juncture is caused to open or change from the closed state to the open state using a first initiator assembly. The initiator assembly is triggered or activated by one or more electrical signals from a vehicle control system. The vehicle control system is involved with determining that a vehicle collision has occurred which is sufficient to cause activation of the first initiator assembly. In one embodiment, when the first initiator assembly is activated, an explosive charge is ignited that results in movement of an initiator piston device that opens the first transfer member at the juncture of the two transfer member sections. When this occurs, fluid flow is achieved between the two transfer member sections and damping fluid can move from one side of the piston head to the other side.
In a preferred embodiment as well, the control assembly includes a temperature compensation assembly. The temperature compensation assembly includes a reservoir for holding damping fluid. The reservoir has particular applicability in receiving and holding damping fluid from the housing chamber due to temperature changes in the damping fluid. For example, when the temperature that the damping fluid is subject to increases, it is necessary to accommodate the increase in volume occupied by the damping fluid at a higher temperature. For proper operation of the control assembly, in connection with the operation of the temperature compensation assembly, a valve is disposed intermediate ends of a conduit or fluid line that is used in interconnecting the housing chamber and the reservoir. The valve enables damping fluid to pass or flow between the housing chamber and the reservoir when the control assembly is unactivated. However, when activated, the valve shuts off or closes so that the path for damping fluid relative to the reservoir is no longer available. When the embodiment of the piston head having no bore is employed, there are two conduits, on opposite sides of the piston head, to provide fluid communication between their associated portions of the housing chamber and the reservoir.
With respect to operation of the control assembly, when there is a front end collision, the seat back moves in a direction from the rear of the vehicle to the front of the vehicle. The seat back movement assembly, which is operably connected thereto, in one embodiment, causes relative movement between parts of the piston assembly. According to one embodiment, the relative movement is between the housing and the piston head/shaft combination of the piston assembly. Such relative movement can be in the form of the housing moving relative to the piston head/shaft or movement of the piston head/shaft while the housing remains stationary. Although the following description is essentially directed to movement of the housing relative to the piston head/shaft, it should be appreciated that the discussion has applicability to an embodiment in which the piston head/shaft move relative to the housing.
The degree, amount and/or rate of relative movement of the housing is a function of the movement of the damping fluid. The greater in number and/or size of damping fluid pathways relative to the housing chamber, the less damping occurs. Conversely stated, the smaller the total volume of damping fluid pathways relative to the housing chamber, the more damping occurs. Assuming for example that the piston head includes one bore and the first initiator assembly has been activated to change the juncture associated with the first initiator assembly from its closed state to its open state, damping fluid is caused to move from the first side of the piston head to its second side through the bore. Continuing with this example and at the same time, damping fluid is also caused to move from the housing chamber in the first direction. This damping fluid moves along, among other possible additional paths, the first and second transfer member sections to the portions of the housing chamber adjacent to the second side of the piston head. As can be appreciated, as the damping fluid moves out of the housing chamber portions adjacent to the first side of the piston head, the piston head is able to move at the predetermined or desired rate in the first direction thereby providing suitable damping of the seat back. As a variation to this example, if the first initiator assembly were not activated but there is a bore in the piston head, piston head movement would be at a lower rate or slower pace, thereby increasing the damping of the seat back.
With regard to a rear end collision, the seat back tends to move towards the back of the vehicle. Consequently, the housing would then move in a second direction, opposite the first direction relative to the piston head and shaft. Depending on the number of initiator assemblies that are activated, as well as the presence or absence of one or more bores in the piston head, a desired damping of the seat back can be accomplished.
Based on the foregoing summary, a number of salient features of the present invention are readily discerned. A control assembly is provided for controlling seat back movement to a desired or predetermined degree. The control assembly is particularly characterized by regulating the flow of damping fluid relative to opposing sides of a piston head. The damping fluid movement is especially controlled by one or more initiator assemblies, which can be selectively activated. One or more bores formed in a piston head can also be utilized in controlling the damping operation. The control assembly can include a temperature compensation assembly that functions to accommodate changes in temperature of the damping fluid. The control assembly constitutes a straightforward and effective design for damping movement of the vehicle seat. The control assembly has a reduced number of parts, can be assembled in an uncomplicated manner and can be provided at a relatively low cost. Additional advantages of the present invention will be come readily apparent from the following discussion, particularly when taken together with the accompanying drawing figures.